einstein said:(-5a^3b^5)^2 / a^4b^3
My working out and answer:
(-5a^3b^5)(-5a^3b^5) / a^4b^3
25a^6b^10 / a^4 b^3
= 25a^2b^7
The book says the answer= -25a^2b^7
Book is correct IF this is the expression: -(5a^3b^5)^2 / (a^4b^3)einstein said:(-5a^3b^5)^2 / a^4b^3
Subhotosh Khan said:einstein said:(-5a^3b^5)^2 / a^4b^3
My working out and answer:
(-5a^3b^5)(-5a^3b^5) / a^4b^3
25a^6b^10 / a^4 b^3
= 25a^2b^7
The book says the answer= -25a^2b^7
Following PEMDAS - both you and book are incorrect (according to the problem as posted).
einstein said:[Can you please elaborate?
Subhotosh Khan said:einstein said:[Can you please elaborate?
Did you read Deniss's reply above??
If you did - read it again slowly and carefully ......
Denis said:Your work:
25a^6b^10 / a^4 b^3
= 25a^2b^7
That is incorrect (sorry, man!)
As is (no brackets) 25a^6b^10 / a^4 b^3 means (25a^6b^10 / a^4) times b^3
You PEMDASed badly :wink:
einstein said:i copied the the question from the book to the forum correctly and always do
mmm4444bot said:einstein said:i copied the the question from the book to the forum correctly and always do
If your book displays the given expression as shown below, then you did not correctly copy the exercise.
\(\displaystyle \frac{(-5 a^3 b^5)^2}{a^4 b^3}\)
If your book displays the given expression the following way, instead, then you could clarify your typing with square brackets as shown in blue.
\(\displaystyle \frac{(-5 a^3 b^5)^2}{a^4} \; b^3\)
[(-5a^3b^5)^2/a^4] b^3
Either way, the factor of -1 is squared, so there is no negation sign in the answer.
einstein said:It displayed it EXACTLY like this:
\(\displaystyle (-5a^3b^5)^2\div a^4b^3\)
which is what i wrote
No, that is not what you posted.
mmm4444bot said:einstein said:It displayed it EXACTLY like this:
\(\displaystyle (-5a^3b^5)^2\div a^4b^3\)
which is what i wrote
No, that is not what you posted.
I read the symbol \(\displaystyle \div\) as a grouping symbol.
I do not read the symbol / as a grouping symbol.
In mathematical formatting, the vinculum (i.e., fraction bar) is a grouping symbol. We text it as /, and it must be used with grouping symbols added around the denominator.
You typed no grouping symbols, in your original post.
If you still don't understand this error, you might want to ask for additional explanation because this particular issue (failure to text grouping symbols in conjunction with using a forward slash) is the bane of the majority of people asking for help here with exercises that contain rational expressions.
einstein said:So what you're saying is:
\(\displaystyle \frac{2+2}{2+2}= 2+2 / 2+2 = 1\)
Whereas:
\(\displaystyle 2 + 2 \div 2 + 2 = 5\)
mmm4444bot said:In mathematical formatting, the vinculum (i.e., fraction bar) is a grouping symbol.
We text it as /, and it must be used with grouping symbols added around the denominator.
lookagain said:einstein said:So what you're saying is:
\(\displaystyle \frac{2+2}{2+2}= 2+2 / 2+2 = 1\)
Whereas:
\(\displaystyle 2 + 2 \div 2 + 2 = 5\)
mmm4444bot said:In mathematical formatting, the vinculum (i.e., fraction bar) is a grouping symbol.
We text it as /, and it must be used with grouping symbols added around the denominator.
No, user einstein, look at the highlighted quote box for user mmm4444bot. For your example,
you have to have grouping symbols around the denominator, *and* also around the numerator,
*in this particular case*, because the numerator has more terms than a monomial.
So, your example must be as \(\displaystyle ** :\)
\(\displaystyle \frac{2 + 2}{2 + 2} \ = \ {(2 + 2)}/{(2 + 2)} \ = \ 4/4 \ = \ 1\)
\(\displaystyle 2 + 2 \div 2 + 2 \ = \ 2 + 1 + 2 \ = \ 5, \ \ and \ this \ is \ correct.\)
\(\displaystyle ** \ \ or \ square \ brackets \ or \ braces\)
einstein said:Okay so i have to put quotes around both numerator and denominator in this forum if i use a forward slash character in an expression. Is that what you guys are saying? <-------YES!!! By George, I think he's got it.
So basically what youre saying is typing an expression like this: 4*2/2+1 is wrong, not valid, doesn't mean anything.<-----No, we're saying its VERY SPECIFIC meaning is "four times two, the result then divided by two, and THEN one added to that result." I have to type it like this in the forum: (4*2)/(2+1).<----Yes, if what you mean is to multiply four times 2, and then divided that result by the sum of 2 plus 1.
But what if i actually want to say and mean: 4 TIMES 2 DIVIDED BY 2 PLUS 1. Well, as you've been told MULTIPLE TIMES in this forum, either use LaTex to write it in fraction form as it probably appears in your text, OR use grouping symbols and write it as (4*2)/(2 + 1). Grouping symbols are not that difficult to type, and will clear up any ambiguity about WHAT belongs WHERE. Then what am i supposed to do when typing that in the forum since i cannot use the forward slash without brackets like you have stated.<----I guess that if typing grouping symbols is too much effort for you to make, then perhaps you could look for a different forum from which to seek help.
Mrspi said:einstein said:So basically what youre saying is typing an expression like this: 4*2/2+1 is wrong, not valid, doesn't mean anything.<-----No, we're saying its VERY SPECIFIC meaning is "four times two, the result then divided by two, and THEN one added to that result."
Mrspi said:Well, as you've been told MULTIPLE TIMES in this forum, either use LaTex to write it in fraction form as it probably appears in your text, OR use grouping symbols and write it as (4*2)/(2 + 1). Grouping symbols are not that difficult to type, and will clear up any ambiguity about WHAT belongs WHERE.
einstein said:The book printed the question like this: \(\displaystyle (-5a^3b^5)^2\div a^4b^3\) and i wrote that in the forum like this: (-5a^3b^5)^2 / a^4b^3
So i was right all along. <<<< No you were NOT